Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.
Electronic devices often require some form of enablement protocol to activate them or to enable a particular function. For example to activate a mobile phone or to log on to a computer system a user may need to enter an alphanumeric code e.g. ‘123’. A known drawback here is that if an unauthorised person learns the alphanumeric code, it is simple for them to activate the mobile phone or log in to the computer system. If the device is equipped with a touch screen so that the alphanumeric keys can be shown on a display, an additional level of security is available in that the locations of the keys can be scrambled either before or during entry of the code, making it more difficult for another person to learn the code by observation. However once the code is known, it is once again simple for an unauthorised person to enter it. US Patent Publication No. 2008/00823015 discloses a non-alphanumeric method for unlocking an electronic device whereby direction keys are used to traverse a path through a displayed maze, and the device is unlocked if the path matches a path preset by the user. Once again, there is no security once the unlock code (i.e. the path) is known, and the restriction to using direction keys limits the range and complexity of possible enablement protocols.
Compared with a keyboard with hard keys, touch screens offer a much greater range of enablement protocols for an electronic device. Apart from the well-known ‘touch to select’ operation mode where a user selects or enables a function by touching a displayed icon, a user can also provide ‘gestural input’ in the form of one or more swipes or taps for example. US Patent Publication No. 2007/0150842 for instance discloses a method for unlocking an electronic device whereby a person touches a displayed image and moves it along an indicated path. Besides unlocking a device, many other functions can be enabled with gestures on a touch screen. US Patent Publication No. 2006/0026535 for instance discloses various mechanisms for interacting with one or more GUI (Graphical User Interface) elements based on a user interface mode and in response to one or more detected touches. The graphical elements that may be activated include a virtual scroll wheel, a virtual keyboard, a toolbar and a control panel. Functions applied include rotating, translating or re-sizing a displayed image, and scrolling through a list. U.S. Pat. Nos. 5,825,352 and 5,943,043 disclose various two finger gestural inputs that emulate mouse functions, while US Patent Publication No. 2007/0177803 discloses the possibility of allowing a user to assign an arbitrary function to a predetermined gesture. However in all these cases the user is either guided by displayed material or the gesture is predetermined, so there is limited opportunity for altering the functionality provided by the device or the mechanisms by which those functions are enabled.
The present disclosure overcomes or ameliorates at least one of the disadvantages of the prior art, and provides a useful alternative.